GB1592130A - Polymerizable mixture of isomers of methylethenylbenzene - Google Patents

Description

PATENTS ACT 1949 SPECIFICATION NO 1592130 The following amendments were allowed under Section 29 on 9 September 1982: Page 2, line 22, for I to 10 read 1 to 3 for 1 to 5 read I to 2 Page 2, line 23, for 90 read 97 for 95 read 98 Page 2, delete lines 25 to 30 Page 3, lines 39 and 40, delete usually at least 95 insert at least 97% Page 4, delete lines 26 to 61 Page 4, for EXAMPLE 3 read EXAMPLE 2 Page 5, TABLE 2, delete whole of Run No. 1, 2 and 3 for Run No. 4,5,6 and 7 read 1,2,3 and 4 Page 5, line 40, delete between runs 3 and 4 insert before run I for 5 and 6 read 2 and 3 Page 5, delete lines 43 and 44, insert Following an initial distillation step to remove any toluene starting material, the ethyl toluene isomer mixture was passed over a complex oxide dehydrogenation catalyst at a temperature of 620 -640 C and at atmospheric pressure. Water was present as a diluent in a water: ethyl toluene weight ratio of 3: 1. The liquid hourly space velocity was 1. 2. Conversion was about 60% per pass and the selectivity 94% for the para-isomer.

The catalyst used was Girdler G-64-C which had the following composition: Wt. percent Fe 55-61 K2CO3 21-25 CE203 4. 65. 6 moto 2 2.2-2.8 The Page 5, for EXAMPLE 4 read 3 Page 5, line 60, for 97.0 rend,. 0 Page 5, line 61, for 3.0 read 97. 0 Page 6, delete lines 33 to 56 Page 6, line 62, for 10% read 3% Page 6, line 63, for 90 read 97 Page 6, line 64, delete isomers are insert I-methyl-2-ethenyl benzene is Page 7, delete lines 1 to 11 insert proportion of 0 to 0.05% by weight.

3. The mixture of claim I or claim 2 when prepared by the catalytic dehydrogenation of a mixture of the corresponding ethyl toluenes prepared by alkylation of toluene with ethylene in the presence of a crystalline aluminosilicate zeolite catalyst having a silica : alumina ratio of at least 12 and a constraint index within the range of 1 to 12.

4. A mixture of methyl ethenyl benzenes substantially as described in the foregoing Examples 2 and 3.

THE PATENT OFFICE 10 November 1982 Bas 93323/9 (54) POLYMERIZABLE MIXTURE OF ISOMERS OF METHYL ETHENYL BENZENE (71) We, MOBIL OIL CORPORATION, a Corporation organised under the laws of the State of New York, United States of America, of 150 East 42nd Street, New York, New York 10017, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement :- This invention relates to a polymerizable mixture of isomeric methylethenyl benzenes and to polymers of such mixtures.

Styrene has been used for a long period of time in the manufacture of polymers and polystyrene has attained a large market for many purposes. Alkylated styrenes such as alpha-methylstyrene have also been of interest for certain purposes.

The nuclear alkyl substituted styrenes have also been used in various applications. The monomer which has been principally used is known as vinyltoluene. This is a mixture which consists mainly of meta-and para-methyl styrenes (vinyl toluenes) produced by the catalytic dehydrogenation of a mixture of the corresponding m-and p-ethyltoluenes. The ethyltoluene mixture is itself obtained by the fractional distillation of a mixture of the o-, mand p-ethyltoluenes. The ratio of the m-and p-isomers in the monomer mixture is approximately 65 : 35 (m: p). A convenient summary of the preparation and properties of the monomer mixture and of polymers produced from it is given in"Styrene: Its Polymers, Copolymers and Derivatives"Ed. R. H. Boundy, R. F. Boyer, ACS Monograph Series, 1952, Hafner Publishing Company, pages 1232 to 1245.

Vinyltoluene is produced by the dehydrogenation of ethyltoluene. Since the ethyltoluene starting material itself comprises a mixture of isomers the vinyl toluene product will also comprise an isomer mixture and the isomeric constitution will approximate that of the original ethyltoluene. Thus, if a different isomeric distribution is desired in the vinyltoluene, the isomer distribution of the ethyltoluene must be modified accordingly.

Processes for producing various mixtures of ethyltoluene isomers are known. In these mixtures, the para isomer has generally been present in an amount less than 40 weight percent with the meta isomer generally present in a major proportion, together with smaller amounts of the ortho isomer. L'. S. 2, 763,702, for example, describes a mixture of ethyltoluene isomers resulting from ethylation of toluene with ethylene in the presence of a Friedel-Crafts catalyst, such as aluminum chloride, containing isomeric mono-ethyltoluenes in relative proportions of from 8 to 3 percent of the ortho isomer, 40 to 65 percent of the meta isomer and from 20 to 40 percent of the para isomer. U. S. 2, 773,862 describes the ethylation of toluene in the presence of an aluminum chloride catalyst to yield an isomeric mixture in which the meta isomer predominates, the para isomer is present to a lesser degree and the ortho isomer is present in still smaller amount. A typical isomer mixture disclosed contains 10 to 20 weight percent of ortho-ethyltoluene, ^5 to 30 weight percent of para-ethyltoluene and 55 to 60 weight percent of meta-ethyltoluene. U. S. 2, 920, 119 refers to a conventional ethyltoluene isomer mixture obtained by ethylation of toluene in the presence of a Friedel-Crafts catalyst. This mixture has a meta isomer content of 72 percent, a para isomer content of 20 percent and an ortho isomer content of 8 percent. U. S.

3D7'0, 7'5 discloses a product mixture containing about 45 percent of ortho-ethvltoluene, about 38 percent para-ethyltoluene and about 3 percent of meta-ethyltoluene. This mixture is obtained by alkylating an aromatic hydrocarbon in the presence of a catalyst comprising a molybdenum halide, an alkylaluminum dihalide and a proton donor.

The presence of substantial quantities of the ortho isomer in the ethyltoluene is highly undesirable because, on dehydrogenation, it tends to undergo ring closure with formation of indenes and indanes which adversely effect the properties of resultant polymer produced from the resultant vinyl toluene. The indenes and indanes are difficult to separate from the vinyl toluene. It has therefore been necessary to remove the ortho isomer from the ethyltoluene by expensive distillation techniques prior to dehydrogenation.

It is evident that the availability of ethyltoluene in which the ortho isomer is either absent or present only in trace amount would eliminate the necessity for expensive prior removal of this isomer. Such products have not previously been available but in our co-pending application No. 19816/78 (Serial No. 1592129) we have described a process for preparing an ethyltoluene isomer mixture which consists almost entirely of the para isomer. The ortho isomer is either entirely absent or present in extremely small amounts.

According to the present invention we provide a mixture of isomers of methyl ethenyl benzene which consists essentially of 1-methyl-2-ethenyl-benzene, 1-methyl-3-ethenyl benzene and 1-methyl-4-ethenyl benzene in which the isomeric distribution is as follows: Range-Wt. percent Isomer Broad Preferred 1-methyl-2-ethenyl benzene 0-0.1 0-0.05 1-methyl-3-ethenyl benzene 1 to 10 1 to 5 1-methyl-4-ethenyl benzene 90 to 99 95 to 99 In preferred mixtures the 1-methyl-4-ethenyl benzene comprises 97 to 99 weight percent (and preferably 98 to 99 weight percent), the 1-methyl-2-ethenyl benzene 0 to 0.1 weight percent (preferably less than 0.05 weight percent) with the 1-methyl-3-ethenyl benzene making up the balance of the ethenyl benzene content (preferably 1 to 3 weight percent).

However, the content of the 1-methyl-4-ethenyl benzene may be allowed to be as low as 95% without serious effects on the resultant polymers.

The isomer mixture may contain impurities and adventitious materials in addition to the methyl ethenyl benzenes. Generally, these other materials will not constitute more than 1 percent by weight of the total mixtue. These other materials derive essentially from the process used to make the methyl ethenyl benzenes.

A typical isomer mixture has the following analysis, by weight, determined by gas chromatography : Wt. percent Total ethenyl benzenes 99.41 Residue: Ethyl toluene 0.10 Mesitylenes etc. 0.15 Non-vinylic higher boilers 0.34 0.59 0.59 100. 00 Ethenyl benzenes: 1-methyl-2-ethenyl benzene 0.05 1-methyl-3-ethenyl benzene 2.6 1-methyl-4-ethenyl benzene 97.4 The mixture of the isomeric methyl ethenyl benzenes may be obtained by the catalytic dehydrogenation of a mixture of the corresponding ethyl toluenes. The dehydrogenation is suitably carried out under the conditions conventionally used for the dehydrogenation of ethyl benzene to form styrene. Thus, the dehydrogenation will generally be carried out in the vapor phase at elevated temperatures in the presence of a dehydrogenation catalyst.

The pressure may be at, above or below atmospheric pressure. Generally, for ease of operation, atmospheric pressure is preferred but a non-reactive diluent may be present to reduce the partial pressure of the ethyltoluene so that the dehydrogenation is effectively carried out under reduced pressure to obtain a favorable equilibrium. Water in the form of steam is a suitable diluent and will generally be present in a major proportion in the feed.

Feed ratios from 1 : 1 to 5 : 1 by weight water to ethyl toluene are generally preferred.

Temperatures of 500 to 750 C are generally used, preferably from 600 to 650 C. Liquid hourly space velocities of about 1.2 (for ethyltoluene) are suitable and preferred.

Conversion is usually about 60% with selectivities of about 94% on the 1-methyl-4-ethenyl benzene isomer. Catalysts are the conventional dehydrogenation type, generally comprising complex oxide mixtures. A typical catalyst comprises ferric oxide, potassium carbonate, cerium oxide and molybdenum oxide as follows : Wt. percent Fe203 55-61 K2CO3 21-25 Ce203 4.6-5.6 (Ce) MoO2 2.2-2.8 The ethyl toluene starting material may be obtained by the process described in our co-pending Patent Appliction No. 19816/78 (Serial No. 1592129). Upon dehydrogenation, the isomeric distribution of the ethyl toluene carries through to the dehydrogenated product and therefore, a product high in the para isomer (1-methyl-4-ethenyl benzene) is obtained.

The ortho isomer (1-methyl-2-ethenyl benzene) is either absent or present in only trace amounts.

The method disclosed in our co-pending application essentially involves the alkylation of toluene with ethylene in the presence of certain crystalline aluminosilicate zeolite catalysts.

The catalyst has a silica: alumina ratio of at least 12 and a constraint index within the range of 1 to 12. The process produces an extremely high proportion of the 1-methyl-4-ethyl benzene isomer, with only a minor proportion of the 1-methyl-3-ethyl benzene isomer and negligible amounts of the 1-methyl-2-ethyl benzene isomer. The almost complete absence of the 1-methyl-2-ethyl isomer is highly advantageous because, as previously mentioned, this isomer tends to produce undesired by-products during the dehydrogenation step (indanes and indenes which adversely affect the properties of the resultant polymers and which cannot be easily separated from the methyl ethenyl benzenes).

The mixture of isomeric methyl ethyl benzenes may be subjected to distillation prior to the dehydrogenation step in order to separate out various by-products and after the dehydrogenation has been completed, a further distillation may be carried out to separate the methyl ethenyl benzenes from their saturated precursors.

Since the proportion of the 1-methyl-4-ethenyl benzene in the mixture is so high, usually at least 95 by weight, the mixture can be regarded essentially as the para (1,4-) isomer.

The mixture of the methyl ethenyl benzene isomers may be polymerized by itself to produce polymers or with other copolymerizable monomers to produce copolymers. In general, the polymerization conditions appropriate to styrene will also be useful with the methyl ethenyl benzene mixture, whether polymerized by itself or with other monomers.

Thus, polymerization may be effected under bulk conditions or in solution, suspension or emulsion, techniques comparable used for styrene polymerization. The polymerization catalysts may be of the free radical, anionic or cationic types. Suitable free radical initiators include di-tertiary butyl peroxide, azobis (isobutyronitrile), di-benzoyl peroxide, tertiary butyl perbenzoate, di-cumylperoxide and potassium persulfate. Cationic initiators are generally of the Lewis acid type, for example, aluminum trichloride, boron trifluoride, boron trifluoride etherate complexes and titanium tetrachloride. Anionic initiators are generally of the organometallic type such as methyl lithium, ethyl lithium, methyl sodium, propyl lithium, n-butyl lithium, sec-but lithium, tert-butyl lithium, butyl sodium, lithium naphthalene, phenyl lithium, or cumyl sodium.

The polymers have useful and valable properties which distinguish them from related materials such as polystyrene.

The following Examples are given to illustrate the invention. Example 1 describes a known procedure for producing the ethyl toluene precursor. This process produces only a small amount of the para isomer.

EXAMPLE 1 To 100 ml. of toluene was added 1 gram of aluminum chloride and ethylene at a rate of 40 cc/minute at a temperature of 80 C. After 2 hours, the composition was that shown in Table 1 below :: TABLE 1 Component Weight percent Benzene 0.20 Toluene 71.90 Ethylbenzene 0.17 Xylene Para 0.15 Meta 0.06 Ortho 0.04 Ethyl Toluene Para 6.43 Meta 14.37 Ortho 3.24 Higher 1.45 Other 1. 99 The para/meta/ortho ethyltoluene ratio was 27/60/13.

EXAMPLE 2 Preparation of catalyst A 5.3 gram sample of the hydrogen form of ZSM-5 having a crystallite size of about 2 microns was steamed at 515 C. for a period of 2 hours and a feed rate of 8.8 cc of liquid water per hour. The temperature was then raised to 640 C. Toluene was then fed at a rate of 180 ml per hour for a period of 4 hours and 15 minutes. The temperature was then reduced to 550 C., the catalyst flushed with nitrogen and then cooled to yield a coke-containing product.

Alkylation of toluene Toluene was alkylated with ethylene in the presence of the above catalyst. The conditions of reaction included a temperature of 300 C., a weight hourly space velocity of 7.4, a molar feed ratio of toluene to ethylene of 5 and a stream time of one hour. The conversion of toluene obtained was 4. 1 weight percent and of ethylene 24.1 weight percent. The ethyltoluene isomer mixture was found to contain 93.15 weight percent of para isomer and 6.85 weight percent of the meta isomer.

Dehydrogenation of ethyltoluene The ethyl toluene isomer mixture was passed over a complex oxide dehydrogenation catalyst at a temperature of 620 -640 C and at atmospheric pressure. Water was present as a diluent in a water: ethyl toluene weight ratio of 3: 1. The liquid hourly space velocity was 1.2. Conversion was about 60% per pass and the selectivity 94% for the para-isomer.

The catalyst used was Girdler G-64-C which had the following composition: Wt. percent Fe203 55-61 KC03 21-25 Ce203 4.6-5.6 M O2 2.2-2.8 The isomeric distribution of the dehydrogenated product was the same as that for the ethyl toluene charge (93.15: 6.85; para: meta; ortho substantially absent).

EXAMPLE 3 Preparation of catalyst HZSM-5 having a crystallite size of 0.02 to 0.05 microns was mixed with 35 weight percent alumina binder and extruded to produce a 1.5 mm. cylindrical particle. A ten gram sample of this extrudate was soaked overnight at room temperature in a solution of 8 grams of 85% phosphoric acid in 10 mi of water. The resulting product was filtered, dried at 120 C. for about 2 hours and calcined at 500 C. for approximately an additional 2 hours.

Ten grams of the phosphorus impregnated extrudate was then soaked at room temperature overnight in a solution of 25 grams of magnesium acetate tetrahydrate in 20 ml of water. It was then filtered, dried at 120 C for about 2 hours and then placed in a furnace at 500 C. for approximately 2 hours. The resulting product contained 4.18 weight percent phosphorous and 7.41 weight percent magnesium.

Alkylation of toluene Toluene was alkylated with ethylene in the presence of the above catalyst. The conditions of reaction and analytical results are summarized in Table 2 below.

TABLE 2 Run No. 1 2 3 4 5 6 7 Temp. C 300 350 350 350 400 400 450 WHSV 7.4 7.4 3.9 3.9 3.9 3.9 3.9 Molar Feed Ratio Toluene/Ethylene 5.1 5.1 2.5 2.5 2.5 2.5 2.5 Stream Time, Hrs. 1 2 3 4 5 6 7 Conversion) Toluene 2.4 7.1 8.2 9.2 8.0 20.1 13.2 Wt. %) Ethylene 1.6 29.3 17.2 55.1 12.7 59.9 2.1 Ethyl Toluene Para 100 100 99.2 98.6 98.04 98.96 98.84 Meta--. 8 1.4 1.88 1.04 1.16 Ortho----. 08.04 Catalyst calcine between runs 3 and 4 and between runs 5 and 6.

Dehydrogenation of ethyltoluene The ethyltoluene product was dehydrogenated using the conditions specified in Example 2 following an initial distillation step to remove any toluene starting material. The dehydrogenated product was also distilled to remove unreacted ethyltoluene.

The isomer distribution of the dehydrogenated product (ortho, meta, para) was equivalent to that of the ethyltoluene starting material in each case.

EXAMPLE 4 Preparation of polymer from mixture of methyl-ethenyl benzene isomers.

The mixture of methyl ethenyl benzene isomers used had the following composition (weight percent): Methyl ethenyl benzenes 99.43 Ethyltoluene 0. 53 Xylenes, cumenes, mesitylenes 0.01 High boiling materials 0.03 Methyl ethenyl benzenes: 1-methyl-2-ethenyl benzene- (1) 1-methyl-3-ethenyl benzene 97.0 1-methyl-4-ethenyl benzene 3.0 Note: (1) Less than 0.05%.

The mixture (120 g.) was dissolve in 46.75 g toluene and 0.168 g azobis (isobutyronitrile) and poured into a dry bottle which was then closed by a coupling/ball valve assembly. Dry nitrogen was then bubbled through the mixture in the bottle for 10 minutes by means of a needle inserted through the septum and the open ball valve. The nitrogen exited through a short needle piercing the septum on top of the ball valve. The two needles were then removed, the ball valve closed and the bottle placed in an oil bath at 60 C for 96 hours and at 90 C for 24 hours.

The polymerized mixture was removed from the bottle by dissolving it in additional toluene at 90 C. The volume of the final solution was about 400 ml. The polymer was then precipitated by pouring the solution into about 1000-1500 ml methanol in a 4 liter blender (Waring Blendor), adjusting the stirring speed to shred the polymer. The liquid was decanted and the polymer washed once with methanol in the blender. The solid polymer was filtered off and dried in a vacuum oven at 100 C under vacuum for 48 hours.

Claims (4)

The properties of the polymer were as follows: Molecular wt (Mv-viscos. Ave) 269 x 10-3 (Mn-number Ave) 158 x 10-3 TG, C 111 Vicat, C 119 Deflection temp. C 98 Melt Index (Cond G) 2.1 Density g/cc 1.008 Break strength, psi 6065 Elongation, % 3 Tensile Modulus: Rheovibron, psi x 10-3 331 Instron, psi x 10-3 338 Impact strength, ft/lb-in 0.20 Haze 4. 4 Transmittance, % 89.7 Pentane uptake 41.0 EXAMPLES 4A, 4B, 4C Polymers prepared in the same way as in Example 4 from similar monomer mixtures containing different proportions of the p-isomer (1-methyl-4-ethenyl benzene) had the following properties : Example 1A 1B 1C p-isomer content, % 89.3 95.5 99.7 Molecular wt (Mv x l0-3) 271 278 269 (Mn x 10-l)-168 177 To,-C 106 110 113 Vicat, C 108 114 118 Deflection temp. C 93 108 104 Melt Index, (Cond G) 3.0 2.4 2.3 Density g/cc 1.014 1.011 1.008 Break strength, psi 6010 5330 5170 Elongation, % 1. 4 8 3 Tensile Modulus Rheovibron, psi x 10-3 363 325 355 Instron, psi x 10-3 309 301 332 Impact Strength, ft/lb-in 0.28 0.13 0. 21 Haze 5. 0 4.2 5.2 Transmittance, % 88.3 88.7 88.7 Pentane uptake 40.0 40.0 40.0 WHAT WE CLAIM IS: 1. A polymerizable mixture of isomers of methyl ethenyl benzene in which the isomers are present in the mixture in the following proportions by weight: 1-methyl-2-ethenyl benzene 0 to 0. 1% 1-methyl-3-ethenyl benzene 1 to 10% % 0

1-methyl-4-ethenyl benzene 90 to 99%.

2. The mixture of claim 1 in which the isomers are present in the mixture in the following proportions by weight: 1-methyl-2-ethenyl benzene 0 to 0.05% 1-methyl-3-ethenyl benzene 1 to 5%

1-methyl-4-ethenyl benzene 95 to 99%.

3. The mixture of claim 2 in which the isomers are present in the following proportions by weight : 1-methyl-2-ethenyl benzene 0 to 0. 05%

1-methyl-3-ethenyl benzene 1 to 3% 1-methyl-4-ethenyl benzene 97 to 99%.

4. A mixture of methyl ethenyl benzene substantially as described in the foregoing Examples 2,3 and 4.